pedersen



(No Model.)

J,T..PEDERSBN. DENTAL HANDPIEGE.

ANDREW BJSRAHAN, PNCITDLTTMO WASHINGTON. D C.

NTTED STATES YPATENT OFFICE.

JOHANNES TH. PEDERSN, OF NEV YORK, N. Y.

DENTAL HANDPIECE.

SPECIFICATION forming part of Letters Patent No. 552,669, dated January 7, 1896. Application led February 1851895.` Serial No. 538,766. (No model.)

To all whom it may concern.'

Beit known that I, JOHANNES THEODOR PEDERSN, a citizen of the United States, residing at the city, county, and State of New York, have invented a :new and useful Improvement in Dental I-Iandpieces, of which the following is a specification.

In dental handpieces as heretofore constructed, the operating-tool was held in the handpiece by a chuck, and the engagement or liberation'of the tool with the chuck was effected by various mechanical devices. These constructions complicated the mechanism and made the handpiece expensive, and required the action of both hands together to release the operating-tool.

The' object of my invention is to simplify the construction and lessen the cost by a handpiece wherein the tool is held by the handpiece mechanism in its normal condition and released by direct and excess pressure of one hand upon the handpiece while holding the same.

In carrying out my invention I employ a flexible case, a tool-holder for holding the operating-tool, and internal mechanism for rotating the tool-holder and tool. Vhile the axial line of the flexible case and internal mechanism is maintained, the tool-holder firmly grips the tool; 'but when the axial line is disturbed by bending or altering the alignment of one part of the case to the other an elongation is produced which releases the grip of the tool-holder upon the tool. This'grip is restored the moment the pressure on the flexible handpiece is released and the parts return to a normal condition of alignment.

The flexible handpiece-case may be made with one part rigid and the other part provided with a pivotal or hinge joint; but I prefer to make said case with the forward or pointed end rigid and the other part screwing therein composed of a helical spring secured to end collars, as the same maintains its alignnient unassisted.

The internal mechanism comprises with the stem from the dental-engine coupling and the rotating sleeves a tool-holder for gripping the tool, an adjusting stem and toggle-bar and `tension spring, said parts being capable of deflection from a straight line for the release a, the collar a and collar a2. have knurled surfaces and parts that extend of the operating-tool from the grip of the chuck.

In the drawings, Figure lis a longitudinal section of my improved dental handpiece. Figs. 2 to 9 inclusive represent elevations of the parts of the internal mechanism. Fig. 10 is an elevation of a modification of my ilexible case. Fig. 1l is a cross-section at fr of Fig. lO, and Fig. l2 is an elevation of a modification of my flexible case. The figures show the parts of about twice the usual size.

The flexible case of my dental handpiece is preferably composed of the rigid taper-case A, whose exterior is preferably roughened or `ribbed to provide a firm hold for the hand,

and the case B composed of the helical spring These collars into the ends of the spring, and to which the spring is soldered to form a rm connection. The collar a is united by a screw-coupling at 2 to the taper-case A, and the end of the collar a2 is threaded for connection with the sleeve that covers the flexible shaft of the dental engine.

In the modification shown in Figs. l0 and ll the flexible portion of the case is made in two parts D D', the sides of the part D being reduced to form opposite flat faces 3 and opposite parts 4 extending out from the part D/ and lapping upon the faces 3, and pins 5 pass through these parts to pivot the parts D and D together. The spring 6 serves to hold these parts in alignment. In the modifica- `tion shown in Fig. 12 the flexible part of the case is cut directly in two portions E E and a hinge-joint 7 connects said parts together. The latch-spring 8, connected to one part and engaging the other part, serves to hold the parts of the case normally together.

Figs. 2 and 3 show separately the sleeves b b, that screw together, and Fig. 4 a short sleeve c, that occupies a position adjoining the end of the sleeve b and in axial line therewith. The sleeve b is provided with an en- -largement 9 and the tapering case A has a shoulder l0 against which the enlargement 9 comes when the sleeve b is introduced into the tapering case A. XVhen the case A and flexible portion are screwed together at the coupln g 2 the end of this coupling comes adjacent to the other end of the enlargement 9, so that a recess-bearing is provided in the tapering case A for the sleeves h and h to prevent end movement. The forward end of the sleeve l) is exteriorly tapering to conform to the interior of the case A and is internally tapering to provide for the action of the holding-jaws d, and the tapering end of the case acts with the jaws CZ to form the tool-holder, hereinafter described. The thickness of the outer end of the sleeve h is increased to provide the internal rib 11.

The holding-jaws d, Fig. 5, are made, as usual, of several compressible end parts and an open center to receive the tool, and the forward ends are tapering and received into the sleeve b, the tapering exteriors of the holding-jaws d an d tapering interior at the end of the sleeve l) coming together, so that longitudinal movement of the holding-jaws either contracts them to grip the tool or permits of their expansion to liberate the tool. The opposite end of the tool-holder is reduced and is received into and fits the left-hand end of the sleeve e, Fig. (3.

The adjustable stem f has a threaded portion 12 near the center and screws into the tapering split end of the sleeve e. The stem f has a screwdriver-notch 13 at one end in the sleeve e and a head 14 with a cup-shaped recess at the other end.

The rod hhas a screw-threaded end to conneet with the dental engine, and the rod near its inner end is reduced and enlarged to-form the head 71/, in the end of which is the cupshaped recess 15.

The split toggle-bar fz', Figs. 1 and 9, is located between the ends of the stem j' and rod h, and it has rounded ends entering the eupshaped recesses in the heads 14 and 71..

A helical spring 7c surrounds the rod h between the collar c and a pin 7c passing through the rod 7L, and the action of this spring is to draw the rod hbackwardly, causing the head h/ to bear firmly against the internal rib 11 of the sleeve h andto keep the parts normally in axial line.

The parts are put together' in the following manner and order: The rod 7L is dropped into the sleeve b, the rib 11 arresting the head 7M. The collar o and spring 7c are then slipped over the rod h, the spring 76 com pressed, and the pin 7c inserted through the rod, thus connecting these parts. The holding-jaws d are inserted in the sleeve e from the left hand and the adjustable stem f from the right hand, and the sleeve and stem are screwed together. The sleeve l) is now passed over the holdingjaws d, sleeve e, and stem f. The toggle e' is then inserted in the sleeve If, and the sleeves b and b are screwed together at the enlargement 9. These parts are then inserted in the taper-case A and the case B is passed over the rod h, and the cases A and B are screwed together at the coupling 2, thus holding the internal parts in place at the enlargement 9. A screwdriver-stem inserted in place of the operating-tool engages the stem f at its notch 13, and rotating said stem in the sleeve tightens or loosens the parts in their axial line to provide for slight variations in the dimensions of the tool-stem, and so controls and brings sufficient pressure. to bear on the holding-jaws to grip the operating-tool C and also-to take up wear of the parts. The dental engine rotates the rod 71. and tool C and all the parts within the connected cases A and B.

To release the operating-tool from the grip of the holding-jaws it is only necessary to bring one part of the case at an angle to the other part and produce an elongation of the axis of the handpiece. This is accomplished by the operation of one hand while holding the handpieee by a pressure of the thumb and fingers bending the helical spring a out of line with the tapering case A, and in so doing moving the rod 7L into the dotted position shown in Fig. 1. This movement rocks the head 7L' upon the rib 11 and swings the toggle e' into the dotted position shown, thus altering the axial line of the toggle and shortening its length between perpendiculars, and at the same time relieving'the pressure on the stem f and holdin g-j aws. The holding-jaws (Z expand by their tapering end moving over the inner tapering surface of the sleeve l), and a slight longitudinal movement is imparted to the holding-jaws Cl, sleeve e., and stem f, and the jaws open and the operating-tool is released and can be removed and another inserted. The release of pressure upon the handpiece permits the springs a and 7a to act and return the parts to a normal condition of alignment, and upon the completion of this movement the pressure upon the holding-j aws is restored and the operating tool firmly gripped by the tool-holder.

In the modification shown in Figs. 10 and 11 the spring G keeps the parts D D' of the handpiece normally in line, and a pressure IOO IIO

when in the hand brings the part D at an angle to the part D to effect the operation of the internal parts, as hereinbefore described.

In the modification shown in Fig. 12, the spring S is unlatched before the part E of the handpiece can be brought at an angle to the part E to effect the opera-tion of the internal parts as hereinbefore described. This latchspring 8 maintains the parts normally in alignment.

The object of splitting the toggle c' is that the end parts thereof may automatically yield and approach one another in the cup of the head 14 and shorten the axial length of the parts in case it develops after the insertion of the operating-tool in the tool-holder that there is too much pressure upon the parts as they approach the axial line to permit of perfect alignment.

Fig. 1 shows the most compact a'nd acceptable form of iiexible case, the one most readily bent and least liable to injure the hand as grasped in use; but I do not limit myself 552,669 y Y s to any particular forni of flexible case for dental handpieces.

The internal mechanism shown is simple and efficient and an arrangement that is effective and that instantly moves out of and returns to the axial line; but I do not limit myself to this precise arrangement.

I claim as my inventionl. In a dental hand piece the combination with the spring tool holding jaws and a iiexible connection between the same and the dental engine shaft for rotating such jaws, of an inclosing case capable of being bent out of a straight line while held in the hand and mechanism acted upon by the bending of the case for releasing the tool from the spring tool holding jaws, substantially as set forth.

2. The combination in a dental hand piece with the rotating shaft, of a tool holder, a

jointed connection from the holder to the dental engine shaft, a sleeve within which the tool holder is revolved and a flexible portion connected with the sleeve and adapted to be bent out of a straight line, substantially as specified, whereby an end motion is given that liberates the tool, substantially as set forth.

In a dental handpiece the combination with a flexible case capable of being bent out of a straight line while held in the hand, of a tapering tube, spring tool holding jaws that slide in said tapering tube, a flexible connection between the engine shaft and the holding jaws, wherebysaid holding jaws are actuated by the bending of the flexible case, substantially as set forth.

4t. The combination with the holder for the operating tool and a surrounding tube, of a flexible connection from the holder to the dental engine shaft for rotating the tool, a tubular case to receive the aforesaid parts and composed of two separable parts screwed together, the one part being rigid and the other part flexible and capable of being bent as held by the hand to curve the axial line and effect an elongation that releases the grip of the holder on the tool, substantially as specified.

5. In a dental hand piece the combination with the holder for the operating tool, means for rotating the same and which means are adapted to be deflected from their axial line, of the rigid case A, the helical spring 0;, and collars a a2 connected to the ends of the helical spring and forming a fiexible case, the collar a screwinginto the caseA and the collar a2 connecting with the covering of the engine shaft, substantially as and for the purposes-set forth.

G. In a dental hand piece the combination i with the tool holder for the operating tool, and

the tubular case, of the connecting sleeves h, b, the stem f, the sleeve c for the said tool holder and stem, the rod h from the dental engine shaft, the collar c, and the spring 7e upon the rod h, and the holding pin k' through the rod h, means for holding the rod h in its relation to the sleeve b and a toggle or equivalent device between the stem fand rod h, substantially as and for the purposes set forth.

7. In a dental hand piece the combination with the tool holder for the operating tool, and the tubular case, of the sleeve b', having an internal rib 1l, the rod h, and a head h' on the same bearing against the rib ll and having a cup-shaped end recess l5, the stem f having a head 14 with a cup-shaped end recess, the split toggle c' with rounded ends resting in the said cup-shaped recesses, substantially as set forth. 1

8. The combination in the dental hand pieceV of a tapering spring tool holder and its surrounding sleeve, means for moving i the tool holder endwise to clamp the tool and a screw intervening between the parts for adj usting the tool holder to different tools, such screw having at its end adjacent to the opening in the tool holder a notch or engaging device for a screw driver introduced through the tool holder, substantially as speciiied.

9. In a dental hand piece the combination with the sleeves, of the tool holding jaws, the internal sleeve e, the threaded adjusting stem f, the rod from the dental engine shaft and a toggle between the adjusting stem fand said rod, substantially as and for the purposes set forth. 95

l0. In a dental hand piece the combination with the sleeves, of the tool holding jaws, the internal sleeve e, the threaded adjusting stem f, the rod from the dental engine shaft, and a split toggle t' between the adjustingstem f roo and said rod, substantially as and for the purposes set forth.

11. In a dental hand piece the combination with the holder for-the tool, of the sleeve b, the connecting sleeve b having an internal 105 rib 11, the rod h having a head 7L bearing against the rib 1l, a collar c around the rod h bearing against the end of the sleeve b', a pin la or stop upon the rod h and a helical spring 7c around the rod h between the pin 7o 1 1o and collar c acting to keep the head 7L seated against the rib l1, substantially as specified.

l2. In a dental hand piece the combination with the holder for the tool, of the sleeve b' connected therewith, the rod 71, passing into 115 the sleeve b the collar c and spring 7c surrounding the rod h and a pin or stop lo connected to said shaft whereby the axial line may be made angular to actuate the tool holder, substantially as set forth.

Signed by me this 7th day of February, A.

JOHANNES TH. PEDERSEN; Witnesses:

Gno. T. PINGKNEY, HAROLD SERRELL. l 

